1. Field of the Invention
The invention relates to a locking and cushioning mechanism, and more particularly to a mechanism for locking and cushioning a spindle of a power tool. The mechanism locks and cushions the spindle when the power tool is powered off.
2. Prior Art
A power tool is an automatic tool having a rotatable spindle disposed inside. The spindle is rotated when the power is inputted to the power tool such that the spindle can output a torsional force for use. In addition, the spindle of the power tool may also provide an impact reaction force under a specific condition.
The spindle is driven by the power to rotate at the high speed, and the spindle is still rotated due to the inertia when the power tool is powered off. Thus, the spindle and its peripheral components generate the impact and noise. The way of solving the impact and noise caused by the inertia of the spindle is to dispose a cushioning mechanism or a locking mechanism within the power tool so that the spindle may be automatically locked when the power tool is powered off.
For example, U.S. Pat. Nos. 7,063,201 and 6,702,090 disclose devices of locking spindles. Each device includes a pair of supporting rings, a locking ring, a snap ring, a releasing ring and several rollers. However, the number of the components of the device is great, and the components cannot be easily assembled.
U.S. Pat. No. 6,454,020 also discloses a device of locking a spindle. The device includes a driving disk, a cam, a plurality of brake pads, a combination of springs and balls, and a cover plate. Although the number of the components is smaller than that of the '201 or '090 patents, the assembling of the springs and the balls tends to become inconvenient due to the influence of the rods extending from an end surface of the driving disk because the springs and the balls are disposed between the driving disk and the cover plate.